There is a continuing need for lower attenuation optical fibers. Low attenuation is one of the most critical properties in optical fibers. Most optical fibers use germania (GeO2) doped silica for the core region and pure silica for the overclad region. However, the Raleigh scattering due to germania doping limits low fiber attenuation to about 0.18 dB/km for practical fibers due to Rayleigh scattering related to dopant concentration fluctuation. To reduce dopant concentration fluctuation, relatively high silica core fibers have been made which utilize a fluorine doped cladding. These fibers sometimes include small amounts of chlorine. However, these high silica content core optical fibers have high viscosity that increases the Rayleigh scattering due to high fictive temperature in the core. In addition, the fluorine (F) doped cladding has a much lower viscosity, which results in high draw induced stress in the core region. The high stress in the core region reduces the glass relaxation, which increases the Rayleigh scattering loss. In addition, the stress effect reduces the core refractive index through stress-optic effects, making it difficult to achieve the core refractive index change required for making a single mode fiber, therefore even higher amounts (˜2×) of fluorine doping in the cladding is required. This higher F-doping makes the silica core and F-doped cladding have even higher viscosity and stress differences, resulting in the fibers being drawn at slow speeds to achieve low attenuation.